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Factors Controlling the Microflora of the Healthy Mouth
Published in Michael J. Hill, Philip D. Marsh, Human Microbial Ecology, 2020
The motile rods of dental plaque are conspicuous in dark field or phase contrast microscopy of wet mounts of plaque samples.49 Several species of oral, Gram-negative rods are motile by means of flagella. Among these are the microaerophilic Campylobacter sputorum and C. concisus, which are curved rods with a single, polar flagellum.81Wolinellarecta and W. curva are anaerobic, Gram-negative rods also having a single flagellum;82 they may previously have been identified as oral Vibrio species. Selenomonas sputigena is a curved to helical, Gram-negative, anaerobic rod with a tuft of flagella near the center of the concave side. Another motile, curved or helical, Gram-negative, anaerobic rod has been characterized recently as Centipeda periodontii. It has 50 or more flagella located in a linear zone, which spirals around the cell, and it shows spreading growth on the surface of blood agar.83,84 Other types of motility than that mediated by flagella are the gliding movement of Capnocytophaga species and the twitching motility of B. gracilis and B. ureolyticus.
Pili and Hosts
Published in Paul Pumpens, Single-Stranded RNA Phages, 2020
A strong interest in the polar, or type IV, or N-monomethylphenylalanine pili was multiplied by discovery of an effect named twitching motility, as a function of P. aeruginosa PAO polar pili. In contrast to the P. aeruginosa PAK strain described above, the pili of the PAO strain were sensitive to the phage PP7 and the latter was used in this revolutionary paper (Bradley 1980a). The twitching motility was formulated as a mode of a primitive motion or flagella-independent surface translocation exhibited by P. aeruginosa and other bacteria on solid media and needed the presence of retractile, usually polar pili, while strains with no pili or non-retractile pili were unable to move, and anti-pilus serum also prevented twitching motility (Bradley 1980a). The subject of twitching motility was thoroughly reviewed at that time by Jørgen Henrichsen (1983), a pioneer in the field, and later by Kaiser (2000), Mattick (2002), and Daum and Gold (2018).
Current concepts in the pathogenesis of periodontitis: from symbiosis to dysbiosis
Published in Journal of Oral Microbiology, 2023
Ali A. Abdulkareem, Firas B. Al-Taweel, Ali J.B. Al-Sharqi, Sarhang S. Gul, Aram Sha, Iain L.C. Chapple
Planktonic bacteria in the oral cavity attach to specific pellicle-associated binding sites such as acidic proline-rich proteins and α-amylase for attachment of early colonizers (Figure 1) [20–22]. Adhesion of bacteria at this stage is mainly dependent upon weak bonds, e.g. Lifshitz-van der Waals, Lewis acid-base and electrostatic interactions [23,24]. The strength of this attachment is increased with the formation of extracellular polymeric matrix (EPM) [25,26]. In addition to the biofilm matrix, attachment of bacteria within the biofilm is mediated by specialized appendages called fimbriae or pili that are composed of subunits called fimbrillins, possessing adhesins that selectively adhere to pellicle-coated teeth or to other bacteria [27]. Fimbriae are common among many bacterial species including Streptococci, Actinomyces and P. gingivalis [28–30]. Furthermore, fibrils also facilitate bacterial attachment; these structures are shorter and different in morphology and distribution from fimbriae [31]. Fibrils can be found in some oral bacteria such as Prevotella intermedia, P. nigrescens, and some Streptococcal strains [28,29,32,33]. Moreover, motile Gram-negative bacteria can utilize force-generating motility as a mechanism for initial attachment to the tooth surface, which counteracts repulsion forces. This active or ‘twitching motility’ is attributed to flagella and type IV pili, respectively [27]. Notably, other surface proteins such as autolysin [34] and capsular polysaccharide [35] also play a role in the attachment of bacteria to solid surfaces.
Design and assessment of novel synthetic peptides to inhibit quorum sensing-dependent biofilm formation in Pseudomonas aeruginosa
Published in Biofouling, 2022
Fatemeh Aflakian, Mehrnaz Rad, Gholamreza Hashemitabar, Milad Lagzian, Mohammad Ramezani
The QS system in P. aeruginosa regulates the expression of the pili and single polar flagella required for bacterial swimming, swarming, and twitching, which is associated with colonization, biofilm formation and various other virulence factors. To investigate the interference of LasR as a central regulator protein in the QS system, with swimming, swarming, and twitching motility of P. aeruginosa ATCC 27853, different agarose plates in the presence of 1/2 × MIC (800µg ml−1) peptides were prepared. All three peptides reduced swimming, and swarming as well as twitching motility, as evidenced by a significant reduction in diameter readings (Figures 7A and B). The results showed that FASK and YDVD peptides were able to reduce swimming and swarming of P. aeruginosa, more than the WSF peptide. Besides FASK and YDVD peptides significantly reduced the twitching motility.
Exposure to low doses of UVA increases biofilm formation in Pseudomonas aeruginosa
Published in Biofouling, 2018
Magdalena Pezzoni, Ramón A. Pizarro, Cristina S. Costa
Although the mechanism by which UVA promotes biofilm formation is still unknown, the current study shows that two parameters involved in cell adhesion are enhanced by UVA exposure: swimming motility and cell surface hydrophobicity. The study of motility is relevant because various studies have suggested that it is essential to P. aeruginosa biofilm formation (Singh et al. 2002; Klausen et al. 2003a; 2003b; Shrout et al. 2006). Swimming motility is a mode of bacterial movement powered by rotating flagella and occurs when individual cells move in liquid environments (Mah and O’Toole 2001). Swarming is defined as rapid multicellular movement of bacteria on a surface, also powered by rotating flagella (Kearns 2010), and twitching motility is surface motility powered by the extension and retraction of type IV pili, which confers slow movements (Mah and O’Toole 2001). The results shown in this study revealed that only swimming motility increases under UVA exposure. Correlation between biofilm formation and swimming motility has been demonstrated previously in a study with clinical isolates of P. aeruginosa (Fonseca et al. 2004); it should be noted that in this study, the authors also report a relationship between biofilm formation and twitching. It has been demonstrated that swimming motility is regulated by the QS subsystem Rhl in P. aeruginosa (O' Toole and Kolter 1998). Previously, Costa et al. (2010) reported that low UVA doses increase the levels of C4-HSL, the signal able to bind the RlhR receptor to activate Rhl-dependent genes. It is therefore possible that the increase in swimming motility observed under UVA is caused by QS induction by UVA.